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E. N'l GR'EENLEAF AND 6.1. HANSEN.

GRANULATOR.

APPLICATION FILED AUG.19. |915.

Patented July 15, 1919.

EDWARD N'. GREENLEAF .AND GEORGE T. HANSEN, 0F SALT LAKE CITY, UTAH, i ASG-NOBS T0 ALLIS-CHERS MANUFACTURING COMPANY, 0F MILWAU- TIE, WISCONSIN, A CORPORATION' 0F DELAWARE.

@murieron Specication of Letters Patent.

Patented July l5, 1919.

,Application led August 19, 1915. Serial No. 46,728.

To all 'whom t may concern: I

Be it known that we, EDWARD N. GREEN- LEAF and GEORGE T. HANSEN, citizens o-f the United States, residing at Salt Lake City, in the county of Salt Lake and State of Utah, have invented a certain new and useful Improvement in Granulators, of which the following is a specification.

This invention relates to improvements in the construction of granulators of the type commonly employed in the reduction of rock, ore, coal `and similar substances.

An object of the invention 'is to provide a granulator' which is simple in construction and ecient in operation. Another object is to provide simple andellicient means for varying the pulp level within a granulator.

A further Objectis to provide means for varying the pulp level without aecting the screenin area of the discharge. Still another object is to produce a simple and compact device for fixing both the size of the product discharged andthe head or level of the material at the discharge end of the mill. Another object is to provide a discharge screen which is self cleaning.

It has been found, especially in the operation of wet grinding tube and, ball mills'used for the reduction of ores, that for certain conditions of operation, such as the kind of material treated, the ratio of reduction, the size of discharged product desired and others, a predetermined level of pulp within the mill is more efficient and desirable than any other. This desirable pulp level is ordinarily somewhere between the periphery and the central aXis of the mill. By operating a wet grinding mill with the pulp level at or near the central axis, it is in most cases impossible to obtain the maximum ratio and rate of reduction, and also to produce a uniform product at the discharge. In an endeavor to provide means for maintaining the most eicient and desirable pulp level in mills of this type, several so-called quick discharge wet grindin ball mills have been developed.. An objection to these mills has been the fact that they were not provided with suitable means which were unaffected by feed variations, for positively adjusting the pulp level Within the mill. In these prior quick discharge mills it has happened that owing to undesirable and uncontrollable excessive variations in the rate of feed,

'bodies would violently impinge upon each other and upon the mill linings, thus practically ruining the mill in a short time.

With the present invention the pulp level necessary to produce the most eflicient grindlng and a uniform rate of discharge is readily established and maintained without permltting undue wear on the grinding elements. The device of the present invention permits establishment of a pulp level which 1s the most ellicient and desirable for any condition of operation and which will not vary in accordance with variations in the rate of feed. The mill of the present inventlon may be readily adapted to any ratio of crushing within certain limits, either when operated as a tube mill or a ball mill and either for wet or dry grinding. By the present invention destruction of the charge of grinding bodies and of the mill liners, due to complete or nearly complete failure of the feed and of resulting loss of the necessary cushioning pulp level, is also avoided.

A clear conception of an embodiment of the invention may be had by referring to the drawing accompanying and forming a part of this specification in which likereference characters designate the same or similar parts in the various views.

Figure 1 is a fragmentary longitudinal section through a wet grinding ball mill, showing the discharge end thereof.

Fig. 2 is a transverse vertical section through a wet grinding ball mill, a portion of some of the elements being broken away, and the section being taken along the line lI-II of Fig. l looklng in the direction of the arrow.

While the invention is disclosed as specilically applied to a wet grinding ball mill, the grinding balls being of the ordinary type and therefore omitted from the disclosure, it should be understood that the invention is applicable to other similar types of granulators.

The portion of the mill ,disclosed in the drawing comprises a casing made up a shell l and an end head 2. A vertical partition which divides the interior of the casing into a grinding chamber 14 and a discharge chamber 15, is mounted within the shell 1. The end head 2 has a trunnion 3 formed integral therewith and located concentrically of the shell 1. The trunnion 3 is rotatably supported in a bearing 4 mounted upon a pedestal, these elements being of usual construction.. The shell 1 is provided with removable sectional shell liners 5, of any suitable formation, while the trunnion 3 and end head 2 are provided with protecting liners 6, 16, respectively.

The partition which divides the mill casing into the grinding and discharge chambers 14, 15, comprises essentially a series of segments each consisting of a nest of radial screen bars 7, and -a perforated sectional Wall 9. The wall 9 is spaced from "the screen bars7 and is located on the discharge side of the partition. The holes or perforations 10 formed in the wall 9 are of suf-V icient size yso that onlyy a small portion of the total number is necessary to permit free passage of the reduced material from the grinding to the discharge chamber of the mill. Plugs 17 which may be made of wood or any other suitable material, are disclosed as having been inserted in the two outer circular rows of perforations 10, and maintain the level of the pulp 18 in the grinding chamber 14 at the point indicated 'in Fig. 1.

Formed directly upon the end head liner 16 and abutting the perforated wall 9, is a series of lifting vanes or ribs 11. The removable bolts 13 clamp the wall 9 directly against the ribs 11, serving also to retain the peripheral portions of the liners 16 in place against the end head 2. The retaining plate 8 engages the inner ends of the screen segments, this plate 8 together with the screen bars 7 and the inner edges of the segments of the wall 9 and liner 16 being held in place by means of removable bolts 12.

During the'normal operation of thel mill, the shell 1 and end head 2 are rotated, causing the grinding bodies within the chamwith the liquid in a wet grinding mill, is

admitted to the chamber 14 at the feed end of the mill. As the material passes through the chamber 14, it is reduced to the desired fineness by the action of the grindin elements, and is thoroughly mixed wit the liquid to form a pulp.

As the material is suiiiciently reduced to pass through the spaces between the screen bars 7, it is carried forward by the liquid and through the screen spaces. The portion of the reduced material which is in 'suspen-` sion with the liquid at the surface of the pulp passing through the screen, is carried through the outer set of unobstructed openings 10 and into the path of the advancingribs 11. The ribs 11, due to the rotation of the mill, advance and elevate the material thus discharged, eventually permitting the same to iow out of the mill through the trunnion 3.

As the grindingl bodies during rotation of the mill, cascade down the charge and strike the pulp 18, they agitate this pulp and produce waves the action of which is to produce a back and forth motion of the thin pulp between the screen Abars 7, thus tending to prevent material from lodging between the bars. The radial disposition of the bars 7 together with the free space formed on both sides of the bars 7, enhances this cleaning action and produces a screen which is self cleaning. As the relatively heavy freely tumbling comminuting substantially radial screen bars 7, these bars are vibrated, thus further augmenting the lautomatic cleansing of the screen.

' that the productdischarged from the mill is not as desired either'in quantity or quality, the pulp level may be varied to produce v bodies impmge against and roll over the the desired results. The nests of screen bars 7 may be readily removed by removal of the adjacent liners 5 and plate 8, after which the plugs 17 may be readily manipulated. The screen bars 7 are removed independently of the wall 9, thus permitting variation of the pulp level without disturbing the perforated wall.

The insertion of the plugs 17 positively fixes the pulp level, and complete removal of the pulp from within the -mlll is impossible. The plugs 17- are prevented from being dislodged by the screen Vbars 7 which prevent such dislodgment.

It should'be understood that it is not desired to be limited to the exact details of construction shown and described, for obvious modifications will occur to a person skilled in the art.

It isclaimed and desired ters Patent,- 1. In combination, a.' casing forming a comminutingchamber, a discharge sizing screen comprising spaced bars located directly adjacent an end of said chamber, and

to secure by Letlevel of liquid in said chamber, said means being spaced from and located on the side of said screen remote from said chamber.

2. In combination, a casin forming a comminuting chamber, a disc arge sizing screen comprising nests of substantially radial bars located directly adjacent an end of means within said casing' for gaging the said chamber, and means Within said casing for gaging the level of liquid in said cham` ber, said means being spaced from and located on the side of said screen remote from said chamber.

'3. In combination, a casing forming a comminuting chamber, a discharge sizing screen comprising spaced bars located directly adjacent an end of said chamber, a perforated Wall Within said casing, vand means for closing some of the perforations of said wall to gage the level of liquid in said chamber, said Wall being spaced from and located 0n the side of said screen remote from said chamber.

4. In combination, a casing forming a comminuting chamber, a discharge sizing screen comprising nests of substantially radial bars located directly adjacent an end of said chamber, a perforated Wall within said casing, and means for closing some of the perforations of said Wall to gage the level of liquid in said chamber, said Wall being spaced from and located on the side of sald screen remote from said chamber.

5. In combination, a casin forming a comminuting chamber, a disc arge sizing screen comprising spaced bars located directly adjacent an end of said chamber, a perforated wall Within said casing, and a plurality of plugs for closing some of the perforatins of said Wall to gage the level of liquid in said chamber, sald Wall beinf'I spaced from and located on the side of sai screen remote from said chamber, and said screen serving to prevent displacement of said plugs.

6. In combination, a casing forming a comminuting chamber, a discharge sizing screen comprising nests of substantially radial bars located directly adjacent an end of said chamber, a perforated Wall Within said casing, and a plurality of plugs for closing seme of thel perforations of said Wall to gage the level of liquid in said chamber, said Wall being spaced from and located on the side of said' screen remote from said chamber, and said screen serving to prevent displacement of said plugs.

In testimony whereof, the signatures of the inventors are aiiixed hereto.

EDWARD N. GREENLEAF. GEORGE T. HANSEN. 

